1. Field of the Invention
The present invention relates to a hinge auto-return device, and more particularly to a hinge auto-return device used for a glass door that is extremely reliable and durable.
2. Description of Related Art
There are two types of hinges commonly used for glass doors. A first type of hinge is attached to the vertical casement and at one side of a glass door. A second type of hinge is attached to an upper or lower doorframe and to the corresponding end of the glass door.
With reference to FIG. 8, the first type of hinge comprises a mounting plate (41) attached to a vertical casement (52), two door mounting plates (51) attached to opposite surfaces of one edge of a glass door (50), and an auto-return device (60). A first edge of the auto-return device (60) is securely attached to the mounting plate (41), and the door mounting plates (51) are pivotally connected at a second edge of the auto-return device (60).
With reference to FIGS. 9-11, the auto-return device (60) comprises a body (61), a pivot hole (62), two parallel guide holes (63), a pivot pin (64), two plugs (66) and two springs (69). The pivot hole (62), previously called xe2x80x9ca spindle hole,xe2x80x9d is longitudinally defined in the body (61). The two parallel guide holes (63) are laterally defined in the body (61) and communicate with the pivot hole (62). The pivot pin (64), previously called xe2x80x9ca spindle,xe2x80x9d has two keyed ends (not numbered) that fit into corresponding keyholes (not shown) in the door mounting plates (51) and is rotatably received in the pivot hole (62) in the body (61). A plug (66), previously called xe2x80x9ca T-shaped member,xe2x80x9d is movably mounted in each guide hole (63). A spring (69) is mounted in each guide hole (63) between the corresponding plug (66) and the door mounting plate (51). The pivot pin (64) is formed with a cylindrical surface and a longitudinal flat segment (65) corresponding to the guide holes (63). Each of the two plugs (66) has an enlarged head (67), previously called a xe2x80x9cbottom,xe2x80x9d and a neck (68), previously called xe2x80x9ca rod,xe2x80x9d extending axially from the enlarged head (67). The enlarged head (67) of the plug (66) presses against the flat segment (65) of the pivot pin (64) and the neck (68) of the plug (66) is inserted into a corresponding one of the two springs (69). When the glass door (50) is opened, the pivot pin (64) turns along with the door mounting plates (51) and the glass door (50), and the head (67) of each of the plugs (66), pressed by the cylindrical surface of the pivot pin (64), moves toward the corresponding spring (69). The spring (69) is compressed by the plug (66). When the glass door (50) is released, the plug (66) is forced by the resilience of the springs (69) to move towards the pivot pin (64) until the head (67) of the plug (66) abuts the flat segment (65) of the pivot pin (64).
With reference to FIG. 12, a second type of hinge comprises a mounting plate (41) attached to horizontal segment of a doorframe (52), two door mounting plates (51) attached to opposite surfaces of an upper end of a glass door (50) and an auto-return device (not numbered). The auto-return device includes a pivot pin (70) formed with two flat longitudinal segments (71) on opposite sides of the pivot pin (70). The pivot pin (70) includes an upper end securely connected to the mounting plate (41) and a lower end extending through a pivot hole (not numbered) defined perpendicular in a center of a body (72). Each sides of the body (72) has two guide holes (73) defined horizontally in the body (72) and communicating with the pivot hole. Each of the guide holes (73) has an inner thread (74) formed at an open end of the guide hole (73) in the body (72). A plug (75) is movably received in the guide hole (73) and abuts one of the flat segments (71) of the pivot pin (70). A spring (76) is received in the guide hole (73) between the plug (75) and a threaded plug (77) screwed into the inner thread (74) at the open end of the guide hole (73).
The conventional hinge auto-return device for glass doors has the following disadvantages.
1. Because the only the outer surface of the enlarged head of the plug abuts the inner surface of the guide hole, the axial alignment of the plugs in the guide holes is unstable. Consequently, the plugs will pivot slightly in the guide holes when the door opens and will reduced the restoration force applied to the pivot pin.
2. The plugs will jam in the guide hole when it is moving along the guide hole when the glass door is opening or closing.
3. As the plug is often excessively abraded during normal operations, the useful life of the auto-return device of a hinge be reduced.
The present invention has arisen to mitigate and/or obviate the disadvantages of the conventional auto-return device of a hinge for a glass door.
The main objective of the present invention is to provide a more reliable hinge auto-return device for a glass door, which will extend the life of the auto-return device.
To achieve the objective, the auto-return device in accordance with the present invention comprises a body containing a longitudinal pivot hole to rotatably receive a pivot pin in the body and a lateral guide hole for movably a receiving a positioning block in the body. The lateral guide hole perpendicularly communicates with the pivot hole. At least one blind hole is longitudinally defined in the positioning block to receive at least one resilient member in the positioning block. The positioning block has a contact face forced by resilience of the resilient member to press against a flat segment of the pivot pin when a hinge with the auto-return device is attached to a glass door. The positioning block is able to slide smoothly in the guide hole in the body of the auto-return device without binding or jamming or experiencing undue wear.